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    <meta charset="UTF-8">
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    <title>Document</title>
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<body>
    <script>
        var a = 15;
        // &&运算符
        console.log(a > 10 && a <= 20); // true && true=>true
        console.log(a > 10 && a < 13); //true && false =>false

        // ||运算符
        console.log(a > 10 || a < 13); //true || false =>true
        console.log(a > 20 || a < 13); // false || false=>false
        // !取反
        console.log(!a > 10);
        console.log(!!!!(a > 10));

    </script>
</body>

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